1. Field of the Invention
The present invention relates to a spindle motor.
2. Description of the Related Art
A hard disk drive (HDD), an information storage device, reads data stored on a disk or writes data to a disk using a read/write head.
The hard disk drive requires a disk driving device capable of driving a disk. In the disk driving device, a small spindle motor is used.
This small-sized spindle motor has used a hydrodynamic bearing assembly. A shaft, a rotating member of the hydrodynamic bearing assembly, and a sleeve, a fixed member thereof, have a lubricating fluid interposed therebetween, such that the shaft is supported by pressure generated in the lubricating fluid.
In addition, a rotor hub rotating together with the shaft and having a recording disk mounted thereon may be disposed on an upper portion of the shaft, and the rotor hub is fixedly coupled to the upper portion of the shaft and has a disk shape in which it is extended in a radial direction based on the shaft. Therefore, the lubricating fluid may also be interposed between an upper surface of the sleeve and the rotor hub.
According to the related art, in manufacturing a base provided in the hard disk drive, a post-processing scheme of die-casting aluminum (Al) and then removing burrs or the like, generated due to the die-casting process has been used.
However, in the die-casting scheme according to the related art, since a process of injecting aluminum (Al) in a molten state into a mold to make a form is performed, large amounts of temperature and pressure are required, such that a large amount of energy may be required in the process and processing time and costs may be increased.
Therefore, in order to solve the problems of the die-casting process, an attempt to manufacture the base through a plastic working process such as press working, or the like, has been conducted. However, in the case of manufacturing the base by press working, since the base may have a uniform thickness, a problem may be generated in coupling a core to the base.
That is, in the case in which a base is manufactured in a die-casting process, the base may be provided with a step, so as to seat the core thereon. However, in the case in which a base is manufactured by pressing a plate material having a uniform thickness, since the thickness of the base is uniform, it may be difficult to form a core seating part on the base.
Japanese Patent Laid-Open Publication No. 2007-198555 discloses that a die-casting base is provided with a step to seat a core thereon.